Method of manufacturing key levers for musical instruments



Jan. 18, 1966 c. FRENCH 3,230,128

METHOD OF MANUFACTURING KEY LEVERS FOR MUSICAL INSTRUMENTS Filed March 16, 1962 2 Sheets-Sheet 1 Jan. 18, 1966 R. c. FRENCH 3,230,128

METHOD OF MANUFACTURING KEY LEVERS FOR MUSICAL INSTRUMENTS Filed March 16, 1962 2 Sheets-Sheet 2 INVENTOR /Z mzd 0. 52m

United States Patent Ohio Filed Mar. 16, 1962, Ser. No. 186,226 7 Claims. (Cl. 156-256)) This invention relates generally to pianos and analogous musical instruments, especially to methods and apparatus for use in manufacturing the key levers of such a musical instrument, and more particularly to methods of attaching key facing material to a keyboard blank and apparatus therefor.

The key levers which are employed in playing pianos and analogous musical instruments commonly comprise a wooden body to which a decorative and wear-resistant facing or veneer is afiixed; and in the past, all of the key bodies for a given instrument have been ordinarily fashioned from a single keyboard blank, usually produced by gluing a number or" narrow boards together. The key facing material has been adhesively secured to this keyboard blank as a unitary member consisting of both the top and the front facings or as separate elements for the top and the front veneers.

Proper positioning of the key facing material is an ever present problem; and because the relative position of the top and front facings is positively established when the facing is produced as a unitary member, this construction reduces the total problem to a certain extent and is, therefore, preferred. However even with the provision of a unitary key facing member, there still is the matter of aligning the facing member with respect to the keyboard blank; and this problem has heretofore been attacked by producing the key facing member with depending bosses adapted to enter cooperatively fashioned depressions in the top surface of the keyboard blank. This latter arrangement has been found to be objectionable because the additional thickness of material at the bosses creates localized areas of greater color intensity; and when the facing member is produced in a plastics molding operation, sinkmarks oftentimes develop at these bosses.

Moreover, utilization of such a boss arrangement for aligning the key facing tends to develop spaces between the front facing and the keyboard blank. For facility in other production operations, the rear edge of the keyboard blank is trued for use as a datum plane from which there are located such things as the depressions used in aligning the facing member. The front edge of the keyboard blank is held to precise parallelism relative to the rear edge only with great difiiculty and expense. Hence, mis-mating of the front edge of the keyboard blank and the front facing may, on occasion, result in cracking of the facing, as for example during an attempt to force the parts into contact for adhesive attachment.

Therefore, a general object of the present invention is to provide a new and improved method of attaching key facings.

Another general object of the invention is to provide new and improved apparatus for attaching key facings.

A more specific object of the invention is to provide a method of attaching key facings which achieves precise positioning of the facing relative to a keyboard blank.

A further object of the invention is to provide a method and apparatus for attaching key facings which avoid cracking of the facing material.

A still further object of the invention is to provide a method and apparatus for attaching key facings which produce a strong and uniform adhesive bond between the facing material and a keyboard blank.

3,Z@,l28 Patented Jan. 18, 1966 These and other objects and features of the invention will become more apparent upon a reading of the following disclosure.

In order that the principles of the invention may be readily understood, a single embodiment thereof, to which the application is not to be restricted, is shown in the accompanying drawings wherein:

FIG. 1 is a perspective view of a keyboard blank fashioned in accordance with the invention;

FIG. 2 is a side elevational view of the keyboard blank of FIG. 1 supported in a press for attachment of key facing material;

FIG. 3 is a view similar to FIG. 2 but showing adhesive having been coated on a portion of the keyboard blank, the thickness of the adhesive layer being exaggerated for purposes of illustration;

FIG. 4 is a perspective view of the adhesive-coated keyboard blank with a section of key facing material positioned thereon;

FIG. 5 is an enlarged plan view of the showing of FIG. 4;

FIG. 6 is a side elevational view in reduced scale of the supported keyboard blank having a key facing element positioned thereon and particularly showing the progressive application of pressure to the top surface of the facing element;

FIG. 7 is a view similar to the showing of FIG. 6 but illustrating application of pressure to the front portion of the facing element;

FIG. 8 is a view similar to the showing of FIGS. 6 and 7, illustrating specifically the simultaneous application of pressure to the top and front portions of the facing element;

FIG. 9 is a fragmentary, cross-sectional view of a pressrgre-applying member, illustrating the construction there- 0 FIG. 10 is a perspective view showing severance of the runners from the rear portions of the facing element;

FIG. 11 is a top plan view of a keyboard blank with a facing member adhesively attached thereto, particularly showing sawing of the front regions of the keyboard blank; and

FIG. 12 is a perspective view of a completed key lever constructed in accordance with the invention.

Referring now in detail to the drawings, specifically to FIG. 1, a keyboard blank indicated generally by the numeral 20 is seen comprised of a number of narrow wooden strips 22 which are edgewise adhesively secured together. The strips 22 are cut from a suitable wood such as maple with widths varying from approximately one and one-half to approximately three inches or more, the grain of the wood running along the major dimension of the strips. When the strips 22 are provided with the grain running in this direction and when the strips are secured together at their lateral edges, the grain pattern in the keyboard blank 20 runs from a front edge 24 to a rear edge 26 thereof. Strong and highly serviceable key levers are cut from a keyboard blank so arranged. In addition, it is convenient to refer to the keyboard blank 20 as having a longitudinal axis extending from the front edge 24 to the back edge 26 because of the corresponding grain pattern. Similarly, it is convenient to refer to the keyboard blank 29 as having a lateral axis extending in a transverse direction relative to the longitudinal axis.

When it is desired to reduce the thickness of the keyboard blank 20 without sacrificing strength, the keyboard blank is provided with an upraised central portion 28 which is defined by a Wooden element adhesively secured to the top surface of the keyboard blank 20 overlying the region which is to be slotted to define bushings for the balance rail pins that establish the fulcrum points for the individual key levers. This wooden element is commonly referred to as a butt-on strip.

In accordance with the present invention, a button strip is roughly shaped and adhesively secured in proper position 'to the keyboard blank 20 before the blank is finished. Thereafter, the keyboard blank and its attached button strip are planed and shaped to finished form and dimension in the same general operation. Minor errors in the positioning of the button strip may thus be corrected by appropriately removing portions of either the keyboard blank proper or the button strip itself or both. A keyboard blank incorporating a precisely positioned button strip results.

After the keyboard blank 28 has been molded to final shape and dimension, it is appropriately drilled and routed to define guide slots and locating bores. As is shown in FIG. 2, the keyboard blank 20 is fashioned with guide slots 30 and 32 for receiving the front rail pins of a natural note key lever and of a sharp note key lever respectively. The keyboard blank is also fashioned with guide slots 34 and 36 for receiving the balance rail pins of a natural note key lever and of a sharp note key lever respectively. In addition, the keyboard blank 20 is arranged to include a number of blind bores 38 opening from the top surface thereof in areas defining sharp note key levers; and as will be seen in FIG. 4, a pair of the bores 38 is provided in each of the regions defining a sharp note key lever, each of the pairs of bores 38 being aligned with the longitudinal axis of the keyboard blank. The purpose of the bores 38 will appear hereinafter.

Advantageously, the slots 30, 32, 34 and 36 are lined with felt, and the front edge of the regions defining the sharp note key levers are lanced prior to application of the key facing material.

In compliance with the usage employed in the immediately preceding paragraphs, the key levers which are used in striking the sharp and fiat notes and which are customarily provided in black color are referred to herein as sharp note key levers for convenience.

After the keyboard blank 20 has been formed to proper shape and dimension and after the preliminary operations have been performed thereon, the keyboard blank is located in a support device indicated generally by the numeral 40 in FIG. 2. The support device 48 comprises a substantially horizontal platform 42 which is adapted to receive the keyboard blank thereon. The support device 40 also includes a heel 44 against which the rear edge 26 of the keyboard blank is abutted; and in addition, the support device 40 incorporates a drip apron 46 for discharging excessive amounts of adhesive material from the front surface of the platform 42.

When the keyboard blank 20 has been situated in proper position on the support device 40, an adhesive material 48 is coated on a portion of the top surface and on a portion of the front edge surface of the keyboard blank as is shown in FIG. 3. The adhesive material 48 is applied over the area to which the key facing material is to be attached, and this adhesive material is applied manually with a brush or a knife, by a spray process, or in any other suitable manner. Advantageously, the adhesive material 48 is selected to be a relatively slow setting adhesive material in order not to rush the positioning of the key facing element or elements.

Turning to FIGS. 4 and 5, a key facing element 58 is seen to include a number of interconnected top coverings 52 and a corresponding number of interconnected front coverings 54, the front coverings 54 being formed integrally with the top coverings 52. The key facing element 50 incorporates the coverings for a series of natural note key levers and defines open regions 56 corresponding to the sharp note key levers; and in par ticular compliance with the illustrated embodiment, the key facing element 50 includes coverings for a series of natural note key levers embracing an octave in interval.

As is well shown in FIG. 5, shallow grooves 58 are employed in outlining the facings for the individual key levers.

The key facing element 50 is desirably fabricated from a resinous thermoplastic material in order that it can be produced with the economies inherent in a plastics molding operation; and in order to maintain proper spatial relationship between the rear portions of the key facing element during its adhesive attachment, the element is molded with runner elements 60 and 62 extending between and interconnecting the rear portions of the key facing element. These runner elements are allowed to remain on the key facing element during adhesive attachment thereof to the keyboard blank 26.

After the keyboard blank 24] has been appropriately coated with adhesive material 48 and before the key fac ing element 50 is mounted on the adhesively coated portion of the blank, a locating plug 64 having depending pins 66 is assembled to the keyboard blank with the pins 66 entering a pair of the bores 38- as is shown in FIGS. 4 and 5. The locating plug 64 is fabricated to possess a transverse dimension which corresponds with the transverse dimension of the open regions 56 in the key facing element. Moreover, the locating plug 64 is selected to possess a longitudinal dimension sufiiciently short to prevent its extending completely to the front edge of the sharp note key region to which it is assembled.

When the locating plug 64 has been mounted on an adhesively coated keyboard blank, a key facing element 50 is positioned in contact with the adhesively coated area of the keyboard blank, those edges of the facing element which define the opposite sides of an open region 56 being disposed in contact with the opposite sides of plug 64 whereby to locate the facing element in a lateral direction with respect to the keyboard blank. The key facing element is positioned in a longitudinal direction with respect to the blank by contacting the front covering 54 with the adhesively coated front edge 24 of the keyboard blank. As will be noted in FIG. 5, the key facing element 50 is separated from the forward edge of the locating plug 64 by a space 68. Space 68 allows longitudinal positioning of the key facing element exclusively by cooperation between the front coverings of the facing element and the front edge of the keyboard blank.

While an aligned pair of bores 38 has been described as being employed in locating the plug 64 relative to the keyboard blank 20 in order to provide precise lateral location of a key facing element 50, it is to be recognized that more than two of the bores may be oriented in the region defining a sharp note key lever for this purpose. Likewise, a single non-round bore may be utilized in conjunction with a cooperatively shaped :pin depending from the plug 64.

After a key facing 50 has been properly positioned on the keyboard blank 20 utilizing a locating plug 64, pressure is applied to the top surface of the key facing element progressively from the front to the rear portions thereof in order to sweep occluded air out of the adhesive material 48 and in order to insure a highly uniform adhesive bond. In compliance with the illustrated embodiment, a shoe 70 is shown in FIG. 6 to be pivotally mounted on independently operable arms 72 and 74-. The arms 72 and 74 are utilized to draw the shoe 76 into engagement with the front portion of the key facing element 50 and thereafter to draw the shoe 70 in a path rearwardly of its point of initial contact with the key facing element. The shoe 70 is desirably recessed to pass the locating plug 64, and the shoe 70 may be arranged to extend the entire length of the keyboard blank 20, as for example when the adhesive material 48 is especially slow in setting, or the shoe 70 may be sectionalized, each section covering a separate octave series corresponding to one of the key facing elements 50.

After the shoe 70 has been directed to sweep over the top surface of key facing element 50 in pressuring con- .5 tact therewith, it is raised out of contact with the key facing element as is shown in FIG. 7. Thereafter, a shoe 76 is urged against the front covering 54 of the key facing element to apply pressure thereto, a reciprocable shaft 78 being connected to the shoe 76 for this purpose.

With reference to FIG. 8, pressure is again applied to the top surface of the key facing element while shoe '76 continues pressuring engagement with the front coverings of the key facing element. Specifically, a platen 80 is directed downwardly against a top surface of shoe 70 by means of a shaft 82 which is coupled to the platen. The pressure applied to the key facing element 50 by the shoe 76 and through the platen 80 is maintained while the adhesive material 48 sets and cures. Ordinarily, the curing of the adhesive material is achieved without the application of heat from an external source.

The above-described sequence of applying pressure to the key facing element 50 is important to the prevention of fracture of the facing either during manufacturing or subsequently in use as a result of residual stresses developed during manufacturing. A common area of failure in the key facing element when the described sequence is not followed is indicated by the numeral 84 in FIG. 12.

It has been found desirable to direct the shoe 70 into contact with the key facing element 50 with a resilient, anti-friction engagement therebetween. Accordingly and with reference to FIG. 9, shoe 70 will be seen comprised of a thick, steel plate 86 to which a resilient pad 83 is attached, pad 88 being fabricated from a rubber compound displaying a moderate durometer. A sheet of leather 90 is secured over the rubber pad 88, and powdered talc is applied to the exposed surface of the leather to provide the desired sliding contact.

It is recognized that shoe 70 and shoe 76 can be connected, in which case some sliding action of the shoe 76 will occur over the front coverings of the key facing element 50 upon shoe 70 being urged into pressuring engagement with the top surface of the facing element. In this latter case, shoe 76 is fabricated in a manner similar to shoe 70; and a powdered talc coating is applied to the exposed surface of shoe 76.

After the adhesive material 48 has cured, attaching the key facing element 50 to the keyboard blank 20, the shoes 7t? and 76 are retracted and plug 64 is removed. Thereafter, the runner elements 60 and 62 are separated from the remainder of the key facing element. In FIG. 10, a circular saw element 92 is shown functioning to sever the runner elements 60 and 62 pursuant to their removal. Next, saw cuts are made in the keyboard blank and the key facing element along the lines defined by the grooves 58. In FIG. 11, a band saw element 94 is shown making a saw cut of this nature. Thereafter, saw cuts are made in the rear portion of the keyboard blank 20 in order to separate the individual key levers therefrom.

A finished, natural note key lever is indicated generally by the numeral 96 in FIG. 12. The key lever 96 will be seen to comprise a wooden body 98 fashioned from the keyboard blank 20 and including an upstanding central portion 100 developed from the button strip. A felt lined bushing 102 is fashioned in the body 98 in the region of the button strip to cooperate with a balance rail pin in defining the fulcrum for the key lever. Furthermore, the key lever 96 includes a top covering 52 and a front covering 54 developed from the key facing element St).

The manner in which the present invention may be practiced and the purposes to which it may be put are evident from the foregoing descriptions; and while a particular embodiment of the invention has been shown, it should be understood, of course, that the invention is not limited thereto since many modifications may be made. These modifications are to be understood as forming a part of this invention insofar as they fall within the true spirit and scope of the appended claims.

The invention is claimed as follows:

1. In a method of manufacturing key levers for a musical instrument, the steps of:

(a) forming a key facing element to include an interconnected plurality of coverings for a series of natural note key levers, further forming said key facing element to define open regions corresponding to the sharp note key levers;

(b) fashioning a keyboard blank to include at least one hole opening from the top surface thereof in an area defining a sharp note key lever;

(c) coating an adhesive material on a portion of the top surface of said keyboard blank;

(d) mounting a locating plug on the top surface of a said sharp note key area and fittedly inserting a depending pin of said plug in a said hole;

(e) positioning said key facing element in contact with an adhesively coated area of said keyboard blank with those edges of said key facing element which define the opposite sides of a said open region contacting said plug to locate said facing element in a lateral direction with respect to said keyboard blank;

(f) applying pressure to said key facing element;

(g) allowing said adhesive material to set whereby to attach said facing element to said keyboard blank;

(h) releasing the pressure;

(i) removing said plug; and

(j) separating individual key levers from said keyboard blank.

2. In a method of manufacturing key levers for a musical instrument, the steps of:

(a) forming a key facing element to include an interconnected plurality of top and front coverings for a series of natural note key levers, further forming said key facing element to define open regions corresponding to the sharp note key levers;

(b) fashioning a keyboard blank to include at least one hole opening from the top surface thereof in an area defining a sharp note key lever;

(c) coating adhesive material on a portion of the top surface of said keyboard blank and on a portion of the front edge surface thereof;

((1) mounting a locating plug on the top surface of a said sharp note key area and fittedly inserting a depending pin of said plug in a said hole;

(e) positioning said key facing element in contact with an adhesively coated area of said keyboard blank with those edges of said facing element which define the opposite sides of a said open region contacting said plug to locate said facing element in a lateral direction with respect to said keyboard blank, further positioning said key facing element so that the interconnected front coverings thereof contact the adhesively coated front edge surface of said keyboard blank to position said facing element in a longitudinal direction with respect to said blank;

(f) applying pressure to said facing element;

(g) allowing said adhesive material to set whereby to attach said facing element to said keyboard blank;

(h) releasing the pressure;

(i) removing said plug; and

(j) separating individual key levers from said keyboard blank.

3. In a method of manufacturing key levers for a musical instrument, the steps of:

(a) forming a key facing element to include an interconnected plurality of top and front coverings for a series of natural note key levers, further forming said key facing element to define open regions corresponding to the sharp note key levers;

(b) fashioning a keyboard blank to include a plurality of holes opening from the top surface thereof in areas defining sharp note key levers;

(c) coating adhesive material on a portion of the top surface of said keyboard blank and on a portion of the front edge surface thereof;

musical instrument, the steps of:

(d) mounting a locating plug on the top surface of a said sharp note key area and fittedly inserting a pinof said plug in a said hole;

(e) positioning said key facing element in contact with an adhesively coated area of said keyboard blank with those edges of said facing element which define the opposite sides of a said open region contacting said plug to locate said facing element in a lateral direction with respect to said keyboard blank, further positioning said key facing element so that the interconnected front coverings thereof contact the adhesively coated front edge surface of said keyboard blank to position said facing element in a longitudinal direction with respect to said blank;

(f) applying pressure to the top surface of said facing element progressively from the front to the rear edges thereof;

(g) applying pressure to the front surface of said facing element in the absence of appreciable pressure being exerted on the top surface thereof;

(h) applying pressure uniformly over said top surface While maintaining pressure on said front surface;

(i) allowing said adhesive material to set whereby to attach said facing element to said keyboard blank;

(j) releasing the pressure;

(k) removing said plug; and

(l) separating individual key levers from said key board blank.

4. In a method of manufacturing key levers for a (a) forming a key facing element to include an interconnected plurality of top and front coverings for a series of natural note key levers, said series comprising an octave in interval, further forming said key facing element to define open regions corresponding to the sharp note key levers;

(b) fashioning a keyboard blank to include a plurality of holes opening from the top surface thereof in areas defining sharp note key levers, further fashioning said blank to include at least one of said holes for each octave interval;

(0) coating adhesive material on a portion of the top surface of said keyboard blank and on a portion of the front edge surface thereof;

(d) mounting a locating plug on the top surface of a said sharp note key area and fittedly inserting a depending pin of said plug in a said hole;

(e) positioning said key facing element in contact with an adhesively coated area of said keyboard blank with those edges of said facing element which define the opposite sides of a said open region cont-acting said plug to locate said facing element in a lateral direction with respect to said keyboard blank, further positioning said key facing element so that the interconnected front coverings thereof contact the adhesively coated front edge surface of said keyboard blank to position said facing element in a longitudinal direction with respect to said blank;

(f) applying pressure to said facing element;

(g) allowing said adhesive material to set whereby to attach said facing element to said keyboard blank;

(h) releasing the pressure;

(i) removing said plug; and

(j) separating individual key levers from said keyboard blank.

5. The method according to claim 1 wherein said key facing element is formed by molding with runners coupling rear portions of said interconnected coverings, wherein said runners remain coupling said rear portions during adhesive attachment of said facing element, and wherein said runners are removed after said adhesive material has set.

6. The method according to claim 1 wherein said keyboard blank is fashioned with a pair of said holes in each of the areas defining a sharp note key lever, wherein each of said pair of holes is aligned parallel with the longitudinal axis of said keyboard blank, and wherein said locating plug is mounted on said blank with depending pins in both of a said pair of holes whereby posi tively to position said plug relative to said blank.

7. The method according to claim 1 wherein said keyboard blank is fashioned with a central, laterally extending rib produced by adhesive attachment of a button strip member prior to planing and shaping of said blank whereupon to plane and shape said button strip member simultaneously with said blank.

References Cited by the Examiner UNITED STATES PATENTS 2,100,652 11/1937 Shimer 156-526 3,032,455 5/1962 Fauser 156-510 3,060,074 10/1962 Good 156-250 FOREIGN PATENTS 231,088 3/1925 Great Britain.

ALEXANDER WYMAN, Primary Examiner.

HAROLD ANSI-IER, Examiner. 

1. IN A METHOD OF MANUFACTURING KEY LEVERS FOR A MUSICAL INSTRUMENT, THE STEPS OF: (A) FORMING A KEY FACING ELEMENT TO INCLUDE AN INTERCONNECTED PLURALITYOF COVERINGS FOR A SERIES OF NATURAL NOTE KEY LEVERS, FURTHER FORMING SAID KEY FACING ELEMENT TO DEFINE OPEN REGIONS CORRESPONDING TO THE SHARP NOTE KEY LEVERS; (B) FASHIONING A KEYBOARD BLANK TO INCLUDE AT LEASE ONE HOLE OPENING FROM THE TOP SURFACE THEREOF IN AN AREA DEFINING A SHARP NOTE KEY LEVER; (C) COATING AN ADHESIVE MATERIAL ON A PORTION OF THE TOP SURFACE OF SAID KEYBOARD BLANK; (D) MOUNTING A LOCATING PLUG ON THE TOP SURFACE OF A SAID SHARP NOTE KEY AREA AND FITTEDLY INSERTING A DEPENDING PIN OF SAID PLUG IN A SAID HOLE; (E) POSITIONING SAID KEY FACING ELEMENT IN CONTACT WITH AN ADHESIVELY COATED AREA OF SAID KEYBOARD BLANK WITH THOSE EDGES OF SAID KEY FACING ELEMENT WHICH DEFINE THE OPPOSITE SIDES OF A SAID OPEN REGION CONTACTING SAID PLUG TO LOCATE SAID FACING ELEMENT IN A LATERAL DIRECTION WITH RESPECT TO SAID KEYBOARD BLANK; (F) APPLYING PRESSURE TO SAID KEY FACING ELEMENT; (G) ALLOWING SAID ADHESIVE MATERIAL TO SET WHEREBY TO ATTACH SAID FACING ELEMENT TO SAID KEYBOARD BLANK; (H) RELEASING THE PRESSURE; (I) REMOVING SAID LUG; AND (J) SEPARATING INDIVIDUAL KEY LEVERS FROM SAID KEYBOARD BLANK. 